The telephony devices of this type very often comprising numerous subscriber units offer more and more functions to the user. One of these functions is that of the responder which makes it possible to receive and transmit messages for those who call and which authorize the return of messages to the user at his request.
A problem posed with this type of device is for the user who may be located far from the base station to know whether he has messages. The user may also have the need to make an announcement and thus desires to know whether his responder is available. This problem is all the more serious when one faces devices that satisfy the DECT standards which may thus comprise a large number of subscriber units.